Pass --undefok to DM and nanobench for more graceful branch failure.

scripts/slave/recipes/skia/skia.expected/Perf-Win7-MSVC-ShuttleA-GPU-HD2000-x86-Release-Trybot.json

 [
   {
     "cmd": [
       "git.bat",
       "fetch"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "name": "git fetch"
   },
   {
@@ skipping 268 matching lines @@
       "--format=%at",
       "-s"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "name": "git show",
     "stdout": "/path/to/tmp/"
   },
   {
     "cmd": [
       "[SLAVE_BUILD]\\skia\\out\\Release\\nanobench",
+      "--undefok",
       "-i",
       "[SLAVE_BUILD]\\skia\\resources",
       "--skps",
       "[SLAVE_BUILD]\\playback\\skps",
       "--nocpu",
       "--dummy-flags",
       "--outResultsFile",
       "[SLAVE_BUILD]\\perfdata\\Perf-Win7-MSVC-ShuttleA-GPU-HD2000-x86-Release-Trybot\\data\\nanobench_164710_1408633190.json",
       "--properties",
       "gitHash",
@@ skipping 25 matching lines @@
       "5",
       "[SLAVE_BUILD]\\perfdata\\Perf-Win7-MSVC-ShuttleA-GPU-HD2000-x86-Release-Trybot\\data",
       "164710",
       "[DEPOT_TOOLS]\\third_party\\gsutil\\gsutil",
       "500"
     ],
     "cwd": "[SLAVE_BUILD]\\skia",
     "name": "Upload Nanobench Results"
   }
 ]